1. Field of the Invention
The present invention is directed to an optical measurement system for determination of an object profile, and more particularly to a system for determination of the object profile based upon position data of scanned points on the object surface.
2. Description of the Prior Art
There has been known in the art an optical measurement system for determination of an object profile based upon the position data on the object surface, for example, as disclosed in Japanese Patent Publication (KOKOKU) No. 61-51722. The system utilizes a light beam such as a laser beam directed to the object surface as being oscillated to scan the object surface. The reflected oscillating light beam is constantly monitored by a detector positioned at a fixed distance from a source of the light beam. The detector then measures by triangulation individual distances to successively scanned points on the object surface to thereby obtain position data with regard to the individual scanned points. Thus obtained distances, which represent a series of height data of the scanned points in relation to a reference plane generally perpendicular to a plane including axes of the light beams incident to and reflected from the object surface, are processed to provide a profile of the object along the scanned points. In the prior system, the detector is configured to have a number of light sensitive elements or photo-detectors such as photo-diodes arranged in a single array extending in the direction of following the reflected light beam from the object surface such that each of the elements can provide an output when sensing the light beam or light energy thereof, which output is therefore indicative of the position of the particular scan point on the object surface at a given time. With this array arrangement of the light sensitive elements having the individual outputs, however, the prior system is required to examine the individual outputs from the elements for providing the position data of the scanned points. Consequently, when it is desired to increase resolution or to have a wide dynamic range by adding more light sensitive elements, the system has to process a correspondingly increased number of outputs from the individual elements with attendant complexity in circuit configuration, which places a severe limitation to increasing resolution or dynamic range of measurement. It is therefore highly desired that the system be configured to have an increased number of the light sensitive elements for increased resolution and dynamic range while reducing the number of the outputs from the elements to be processed.
Another prior art system is known to utilize a camera or a line sensor for obtaining the like position data of the object surface as disclosed, for example, in Japanese Patent Early Publication (KOKAI) No. 58-77609. However, such system is found to suffer from a relatively low processing speed and narrow dynamic range, which renders the system impractical where high processing speed and reliable measurement are of primary concerns.